White Light

White light is nothing but transparent daylight. It includes all the wavelengths of the visible spectrum at the same intensity. In basic terms, the light which looks white to the retina is considered white light. It contains the electromagnetic radiation at all wavelengths in the visible range of the spectrum.

The electromagnetic spectrum contains a set of types of electromagnetic waves, each of varying wavelengths or frequencies. Examples of electromagnetic waves include x-rays, gamma rays, infrared radiation and ultraviolet radiation. The human eye can only see a small fraction of the spectrum of wavelengths. This visible segment of the electromagnetic spectrum is the visible spectrum. It shows the entire spectrum of electromagnetic radiation and highlights the small portion of the spectrum. It is known as the visible spectrum.

Sources of White Light

White light can be produced by various sources, both in space and artificially on earth. The Sun and other stars, for example, are generators of white light. The Sun is the most significant source of white light in our solar system. As for artificial, white LEDs and fluorescent light bulbs can produce white light. Some light bulbs, such as incandescent lamps, do not contain white light.

Electromagnetic Spectrum

The electromagnetic spectrum is the phrase that refers to all known electromagnetic radiation frequencies. The Electromagnetic spectrum ranges from the low frequencies used for standard radio wave communication to gamma radiation at the short-wavelength (high-frequency) end, reaching distances from thousands of kilometres to a fraction of the size of an atom.

The light visible to the naked eye is a small part of the electromagnetic spectrum. The rainbow represents the optical or a visible portion of the electromagnetic spectrum. The infrared rays are located right beyond the red side of a rainbow, and the ultraviolet rays are present above the purple end. Unfortunately, though, they are not visible to the human eye.

Scientifically, electromagnetic radiation of 380 nm and 760 nm (400–790 terahertz) wavelength is visible to the human eye and is hence known as visible light. Other wavelengths such as infrared rays greater than 760 nm wavelength and ultraviolet rays, the wavelength of which is shorter than 380 nm, are often referred to as light.

The wavelength of White Light

Based on the wavelength of light, one can see the visible light. The light is not visible above 700 nm and below 400 nm. The white light is composed of 7 colours: violet, indigo, blue, green, yellow, orange and red. Also known as VIBGYOR. Here, the red colour’s wavelength is 400 nm, and the violet colour’s wavelength is 700 mm. So, white cannot be limited to a single wavelength as it consists of wavelengths of different colours. Hence, the wavelength of the white light is 400 – 700 nm.

Characteristics of White Light

The characteristics of White Light are:

• The colours of the visible spectrum appear when the white light reflects from the prism or diffraction grid.
• The colours differ based on their wavelength.
• Violet has the highest frequency and the shortest wavelength, whereas red has the lowest frequency and longest wavelengths.

FAQs about White Light

Q1. What are the applications of white light?

Answer. Most objects, like the Sun in space, are a natural source of white light. The applications of white light are of different types such as:

• On earth, white fluorescent bulbs, white LEDs and torch lights are few sources of artificial white light.
• White light can be broken into various colours with a device like a prism.

Q2. Why do we see White Light?

Answer. Generally, we see objects around us as the white light surrounds them, usually sunlight or simple room light. White light is a combination of all colours, in approximately equal proportions. The white light is composed of 7 colours: violet, indigo, blue, green, yellow, orange and red. Also known as VIBGYOR.

White objects look white as they reflect all the visible wavelengths of light which shine onto them-so the light always appears white to us. Coloured substances, on the other hand, reflects just a few wavelengths; the rest they absorb. For example, if white light shines on a red ball, the ball usually reflects red light, so we see a red colour only. And the remaining parts of white light like green and blue colours are absorbed by the ball. Likewise, a blue book reflects the blue portion of the white light spectrum which we can see. But, the book absorbs the green and blue colour portions of the white light. Hence we see only the blue colour of the white light which is reflected in the book.